Annular Flux Concentrator Layout for Multi-Coil Inductive Heating

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Solution Overview

Problem

Inductive heating systems for aerosol-generating devices face inefficiencies due to unwanted eddy currents and heating of adjacent parts, particularly when multiple inductor coils are used, leading to reduced performance and undesirable heating of non-target areas.

Innovation Solution

An inductive heating arrangement featuring a flux concentrator with an annular channel that distorts and focuses the magnetic field, minimizing its propagation beyond the inductor coil and reducing unwanted induction in adjacent conductive parts, while allowing separate heating of multiple susceptors or aerosol-forming substrates using multiple inductor coils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If inductive heating is used to heat aerosol-forming substrate, then heating efficiency is improved, but unwanted eddy currents and heating of adjacent parts occur

Engineering Contradiction:
Improveheating efficiencyVSAvoidunwanted heating of adjacent parts
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

A magnetic shield is introduced as an intermediary component between the inductor coil and adjacent parts. This magnetic shield intercepts and redirects magnetic flux lines, preventing them from inducing eddy currents in adjacent conductive components. The magnetic shield acts as a mediator that allows the inductive heating system to maintain high heating efficiency while eliminating the harmful side effect of unwanted heating in adjacent parts.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple inductor coils are used to heat different portions of susceptor, then heating versatility is improved, but magnetic field interference between coils occurs

Engineering Contradiction:
Improveheating versatilityVSAvoidmagnetic field interference
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system divides the heating function into multiple independent inductor coils, each responsible for heating a specific portion of the susceptor. Magnetic shields are placed between adjacent coils to segment the magnetic fields, preventing interference between them. This segmentation approach allows each coil to operate independently and efficiently, maintaining high heating versatility while eliminating energy loss due to magnetic field interference.

Inventive Principle:
Principle #1Segmentation

3Productivity

If inductor coil is exposed to aerosol-generating article, then direct heating is improved, but cleaning difficulty increases

Engineering Contradiction:
Improvedirect heating efficiencyVSAvoidcleaning ease
Core Design Contradiction:
ProductivityVSEase of repair

Solution Approach 1:

A susceptor is introduced as an intermediary component between the inductor coil and the aerosol-generating article. The susceptor is heated inductively and then transfers thermal energy to the aerosol-forming substrate through thermal conduction. This indirect heating approach maintains high heating efficiency while allowing the inductor coil to remain isolated from the aerosol-generating article, making cleaning and maintenance much easier.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enhances the efficiency of the heating process by concentrating the magnetic field on the intended susceptor, reducing unwanted heating of adjacent components and improving the overall performance of the aerosol-generating device.

Implementation Method 1

The inductor coil generates a varying magnetic field to generate eddy currents and hysteresis losses in the susceptor, causing the susceptor to heat up

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

The inductor coil generates a varying magnetic field to generate eddy currents and hysteresis losses in the susceptor, causing the susceptor to heat up

Methodology Applied
Scientific EffectHysteresis losses: Magnetic Hysteresis

Implementation Method 3

The inductor coil generates a varying magnetic field

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 4

the flux concentrator distorts the varying magnetic field generated by the first inductor coil

Methodology Applied
Scientific EffectMagnetic flux concentration: Magnetic Field

Implementation Method 5

the annular channel may reduce or minimise the extent to which the varying magnetic field propagates beyond the first inductor coil

Methodology Applied
Scientific EffectMagnetic field confinement: Magnetic Field

Data Source

PatentEP3993652B1An inductive heating arrangement having an annular channel
Publication Date: 2023.08.30 PHILIP MORRIS PRODUCTS SA
  • EP3993652B1 patent drawingFigure 1~2
  • EP3993652B1 patent drawingFigure 3
  • EP3993652B1 patent drawingFigure 4

AI summary

There is provided an inductive heating arrangement (10). The inductive heating arrangement (10) comprises a first inductor coil (12) arranged to generate a first varying magnetic field when a varying electric current flows through the first inductor coil (12). The inductive heating arrangement (10) also comprises a second inductor coil (14) arranged to generate a second varying magnetic field when a varying electric current flows through the second inductor coil (14). The inductive heating arrangement (10) also comprises a flux concentrator (20) positioned around the first inductor coil (12) to distort the first varying magnetic field generated by the first inductor coil (12). The flux concentrator (20) has a tubular shape and comprises a main portion (24) positioned around the first inductor coil (12). The main portion (24) has an inner diameter, a first end and a second end. The flux concentrator (20) also comprises a first end portion (26) at the first end of the main portion (24). The first end portion (26) has an inner diameter, wherein the inner diameter of the first end portion (26) is smaller than the inner diameter of the main portion (24). The flux concentrator (20) also comprise a second end portion (28) at the second end of the main portion (24). The second end portion (28) has an inner diameter, wherein the inner diameter of the second end portion (28) is smaller than the inner diameter of the main portion (24). An inner surface (30) of the flux concentrator (20) defines an annular channel (32) between the first end portion (26) and the second end portion (28). The first inductor coil (12) is positioned within the annular channel (32) between the first end portion (26) and the second end portion (28).